Anthelmintic method and formulations employing phenylhydrazone derivatives

ABSTRACT

Certain new ar or ar&#39;&#39; (alkylthio) benzoyl chloride phenylhydrazones have been found to be effective, broad-spectrum anthelmintics for suppressing parasitic worms in animals particularly sheep. The method of using the new compounds and new anthelmintic formulations are described. The new compound p(methylthio)benzoyl chloride phenylhydrazone is effective at rates at least as low as 100 mg. per kilogram of body weight in sheep. The compounds are readily prepared by conventional chemical reactions.

United States Patent [1 1 Folz ANTHELMINTIC METHOD AND FORMULATIONS EMPLOYING PHENYLHYDRAZONE DERIVATIVES [75] Inventor: Sylvester D. Folz, Kalamazoo, Mich.

[.73] Assigneei The Upjohn Company, Kalamazoo,

Mich.

[22] Filed: July 13, 1970 [21] Appl. No.: 54,621

7 521 US. Cl ..424/327 [51] Int. Cl. ..A6lk 27/00 [58] Field of Search ..260/566 B, 566 D; 424/327 [56] j References Cited UNITEDSTATES PATENTS 3,235,447 2/1966 Urbschat et a1. ..424/327 51March 20', 1973 3,636,112 1/1972 Draberetal..... ..424/327 Primary Examiner-Sam Rosen Attorney-Carl A. Randles, Jr. and John Kekich [57] ABSTRACT Certain new ar or ar' (alkylthio) benzoyl chloride 34 Claims, No I W H H SUMMARY OF INVENTION This invention pertains to a new method for killing and controlling (suppressing growth and reproduction of) worms (Helmint'hs), and new formulations for killing and controlling worms in animals. The invention more particularly pertains to a new method for killing and controlling parasitic worms in animals with new ar or ar (alkylthio) benzoyl chloride phenylhydrazones, and new anthelmint'ic formulations comprising the new compounds for the stated new method.

Parasitic worm infections cause unmeasured but certainly great losses and inefficiency in the production of economic livestock, e.g., cattle, sheep, goats, swine, and poultry; and in the care and maintenance of pets, e.g., dogs, cats, and horses. This invention contributes further to the progress that man has already achieved in his efforts to keep his economic livestock and pets healthy and contented.

One objective of this invention is to describe how some new ar or ar (alkylthio) benzoyl chloride phenylhydrazones can be used to curb helminth parasitism in animals. Another objective is to show various anthelmintic formulations of arm ar (alkylthio) benzoyl chloride phenylhydrazones, and how they can be administered to worm infected animals for killing and control of the helminth parasites. The formulations of the invention can be administered to animals for prophylactic treatment of infections. These and other objectives of the invention will become apparent in the detailed description that follows.

DETAILED DESCRIPTION OF THE INVENTION chloride phenylhydrazones have the structural formula:

my) 11 III (Y)... Q -C=NN &

wherein alkyl is of from one to six carbon atoms, inclusive; X is halogen, i.e., chlorine, bromine, iodine, and fluorine, nitro, alkyl of from one to six carbon atoms, inclusive, a-F alkyl of from one to three carbon atoms, inclusive, and alkylthio of from one to six carbon atoms, inclusive; Y is alkyl of from one to six carbon atoms, inclusive, a-F alkyl as defined above, halogen, nitro and alkylthio as defined above; n is an integer to 3, inclusive; n" is one except when Y is alkylthio, when it can be zero; and m is an integer from 0 to 3, inclusive, the sum of n'+n"+ m being not more than 6, the sum of carbon atoms in alkyl substituents being not'more than 15, there being no more than one nitro group in the molecule, and not more than two S-alkyl groups on any one benzene ring or three total in the molecule.

The new compounds of this invention, for example, p-(alkylthio)benzoyl chloride phenylhydrazones, illustratively, p-(methylthio)benzoyl chloride phenylhydrazone are effective against worms, particularly parasitic worms of animals, and more particularly helminths parasitic in ovines (sheep).

Activity of the new ar or a'r (alkylthio) benzoyl chloride phenylhydrazones was initially observed against Nematospiroides dubius. and Syphaciiz obvelata in mice. Further observations in lambs naturally infected with Haemonchus, Ostertagia, Trichos'trongylus, Nematodirus, Strongyloides, Oesophagosto'mum, Bunostomum, Trichuris, and/or Moniezia showed that the compounds are active at practical low dosages, and that they possess broad-spectrum activity, e.g., against both roundworms and tapeworms.

A preliminary test with lambs was effected by maintaining worm infected lambs under satisfactory environmental conditions with feed and water available ad libitum. Pretreatment fecal examinations were made in order to characterize and evaluate and parasitism of each animal. The presence of helminth ova was recorded in terms of the number of eggs per gram of feces.

On the'day of treatment, each lamb was weighed and a dosage for it was calculated in terms of milligrams of new compound per kilogram of body weight. The'calculated dosage of compound was pulverized and packed in a gelatin capsule for oral administration.

In this preliminary test one lamb received 250 mg. p- (methylthio)benzoyl chloride phenylhydrazone per kilogram of body weight a total dosage of 5.4 g. After treatment, there was significantly fewer helminth eggs in the feces, and reduced numbers of helminths at necropsy thus indicating that the 250 mg./kg. dosage was somewhat effective. Better results at evenvlower dosages were achieved in subsequent tests.

Another lamp received 300 mg./kg. of the compound a total dosage of 8.3 g. In this case, all helminth egg counts were reduced significantly and on necropsy worm infection was found to be low. The egg counts and observations at necropsy established activity against Haemonchus, Ostertagia, Trichostrongylus, Nematodirus, and Strongyloides.

Still another lamb received 400 mg./kg. of the compound a total dosage of 8.0 g. Activity against Haemonchus, Ostertagia, Trichostrongylus, and Strongyloides was established by significantiy lowered egg counts and absence of worms at hecropsy. There was lack of noticeable activity against Trichuris ovis. According to this preliminary test, the compound is established as useful for killing and controlling worms in sheep.

Further, the compound and the other compounds of the invention are contemplated as'useful for killing and controlling parasitic worms in ovines, bovines, equines, porcines, aves, canines, felines, piscines and other animals.

EXAMPLE 1 A subsequent, similar,- but more extensive test showed excellent activity at mg. and 200 mg. per kilogram of body weight. At the 200 mg./kg. dosage, the compound p-(methylthio)benzoyl chloride phenylhydrazone was efficacious against Haemonchus, Ostertagia, Nematodirus, Trichostrongylus, Strongyloides, Oesophagostomum, and Cooperia. At this dosage, activity against the tapeworm Moniezia was observed.

At the 100 mg./kg. dosage, similar broad spectrum anthelmintic activity was observed, including activity against Moniezia. in view of the absence of signs of toxicity of the compound to the lambs, an advantageous anthelmintic agent has been discovered.

In the comprehensive test with lOO mg./kg. and 200 mg./kg. dosages of p-(methylthio)benzoyl chloride phenylhydrazone, five lambs were used for each dosage level, and five lambs were maintained as unmedicated controls. Daily egg counts in the feces were made before and after treatment. The lambs were killed and examined post-mortem for worms present 11 days after treatment. Helminth populations were recovered, enumerated and identified.

The mean percentage efficacy against specific helminths in the test lambs was calculated by subtracting the average number of the helminths observed in the treated lambs, post-mortem, from the average number observed in the unmedicated controls, post-mortem; dividing the remainder by the latter average number; and multiplying by 100. Accordingly, the means percentage efficacies against the various helminths identified in the test lambs were calculated and found to be as follows:

Helminlh 100 mgJkg. 200 mgJkg.

Haemanchur 100 99.9 Ostertagia l 100 Trichortrongylus 99.3 99.9 Nzmarodirus 100 I00 Sirongylaides 100 99.9 Oesophagosromum 90.6 100 Bunortomum Cooperia 100' 100 Tn'churis 0 Tapeworm positive positive only one lamb infected parasites not present.

The total numbers of various helminths found in the non-medicated control lambs, post-mortem, were as follows:

The total numbers of the various helminths found in 20 the 100 mg./kg. dosage group, post-mortem, were as follows:

The total numbers of the various helminths found in the 200 mg./kg. dosage group, post-mortem, were as follows:

NON-VMEIDVICATED coN'TRotl GRoUe 1')A'IAIOTAL NUMBER or PARASIIES necovennn A'I NECROISY Iielminth Haemon- Oster- Tricho- Nemato Strongy- Ocsopha- Buno- Coop- Tri- Tape- Lamb Number chus tagia strongyius dirus loides gostomuin stomum eria churis worm 16 11 2 ll 1 5 130 40 1, 110 430 50 1, 210 640 190 710 6 360 2 180 38 4 29 I 31 3 930 260 v 40 18 30 86 Total number of parasites remaining 1, 366 912 1. 459 76 610 25 90 421 141 Average number of parasites rcmaining 273 182 292 19 122 8 45 28 Number lambs infected at necropsy 5 5 5 4 5 3 2 3 5 =No infection (or very light infection). ;larasitisn1 detected as indicated by Elfi date, but no parasites recovered.

TREATMENT A'l looMtL/KU. GROUP DATA-TOTAL NUMBER OF iAltASi'liCH itl('.()\i'11tii) AI NECROI'SY llelnilntli llaemon- ()ster- 'Iricho- Nemnto- Strong ()esophnliuno- Coop- 'Iri- 'Iape- Lnmb Number ehus tagia strongylus dirus l0i( es gostomum stomum eriu churis worm 0 0 f) 0 0 2 0 f) 6 0 fl 86 0 0 f) 0 0 3 O 0 O 0 0 0 85 f) 0 (l 0 27 Total number of parasites remaining 0 0 6 0 0 3 0 350 0 Average number of parasites remaining 0 0 2 O 0 1 0 70 0 Percent efficacy 100 100 99. 3 100 100 90. 6 100 0 Positive =No infection (or very light infection). 0= Parasitism detected as indicated by EPG data, but no parasites recovered.

TREATMENT AT 200 MGJKU. GROUP DATATOTAL NUMBER OF PARASITES RECOVERED AT NECROPSY lIelminth Iiaemmn ()ster- Tricho- Ncmnto- Strongy- Oesoplm- Buno- Coop- 'Iri- Tape- Lnmb Number i-hus tugia strongyius dirus loides gostomum stomum cria churis worm 0 0 e e 0 s5 0 u 0 0 2 14 0 u n 0 0 4 1 0 2 n e 0 50 0 1 0 0 0 ii 0 Total number of parasites remaining .2 0 J 0 2 0 0 242 0 Average number of pornsites renmining 1 0 1 0 1 0 0 48 0 Percent eflieeey 90. 9 100 99. e 100 99.9 100 100 0 Positive N0 infection (or very light infection).

0=Pnmsitism detected as indicated by EPG data, but no parasites recovered.

a gelatin capsule. This uncomplicated form and route o f administrati on is convenientfor the compounds of this' 'inventio nbecause they are solids at room temperature and they are not very soluble (almost insoluble) in water. A single does was administered, but multiple doses can be used.

Other forms and routes of administration, and other formulations of the active ingredient are contemplated as'embodiments of this invention. For example, aqueous or oil suspensions can be administered orally, or the compounds can be formulated with a solid carrier for feeding. Furthermore, an oil suspension can be converted into an aqueous emulsion by mixing with water and injecting the emulsion intramuscularly, subcutaneously or into the peritoneal cavity.

Pure compounds, mixtures of the active compounds, or combinations thereof with a solid carrier can be administered in the animals, food, or administered in the form of tablets, pills, boluses, wafers, and other conventional unit dosage forms. All of these various forms of the active compounds of this invention can be prepared using physiologically acceptable carriers and known method of formulation and manufacture.

Representative solid carriers'conveniently available and satisfactory for physiologically acceptable, unit dosage formulations include corn starch, powdered lactose, powdered sucrose, talc, stearic acid, magnesium stearate, finely divided bentonite, and the like. The active agent can be mixed with a carrier in varying proportions from, for example, about 0.001 per cent by weight in'animal food to about 90 or 95 per cent or more ina pill or capsule. In the latter form, one'might use no more carrier than sufficient to bind the particles of active compound.

The compounds of this invention should be mixed with animal feeds, in a way that willavoid degradation of the compound. The chlorine atom on the carbonyl carbon is substantially reactive, and amino groups and enzymes present in a feed might promote degradation.

Certain kinds of animal feeds such as whole oats will give no problem, but other such as ground feed mixescan. Accordingly, administration to animals via their feed will require some information, judgment, and evaluation.

In general, the compounds can be formulated in stable powders 'or granules for mixing in an amount of feed for a single feeding or enough feed for one day and thus obtain therapeutic efficacy without complication. It is the prepared and stored feeds or feed premixes that require care. A recommended practice is to coat a granular formulation to protect and preserve the active ingredient. A prepared hog-feed containing about 0.2 percent of the active compound will provide a dosage of about 100 mg. per kg. body weight for each 100 lb. pig in its daily ration.

A solid diluent carrier need not be a homogeneous entity, but mixtures of different diluent carriers can be used. Moreover, formulations with a solid carrier can include small proportions of adjuvants such as water; alcohols; protein solutions and suspensions like skinned milk; edible oils; sugar solutions, e.g., syrups; and organic adjuvants such as propylene glycols, sorbitol, glycerol, diethyl carbonate, and the like.

The solid carrier formulations of the invention are conveniently prepared in unit dosage forms, to facilitate administration to animals. Accordingly, several large boluses (about 20 g. weight) amounting to about 54 g. of active compound would be required for a single dosage to a 900 lb. horse at a dosage rate of mg./kg. of body weight. Similarly, a 60 lb. lamb at a dosage rate of 100 mg./kg. of body weight would require a pill, capsule, or bolus containing about 2.7 g. of active compound. A small dog, on the other hand, weighing about 20 lbs., would require a total dosage of about 225 mg. at a dosage rate of 25 mg./kg. of body weight. The solid, unit dosage forms can be conveniently prepared in various sizes and concentrations of active ingredient, to accommodate treatment of the various sizes of animals that are parasitized by worms.

Liquid formulations can also be used. Representative liquid formulations include aqueous (including isotonic saline) suspensions, oil solutions and suspensions, and oil in water emulsions. Aqueous suspensions are obtained by dispersing the active compound in water, preferably including a suitable surface-active dispersing agent such as a cationic, anionic, or nonionic surface-active agents. Representative suitable ones are polyoxyalkylene derivatives of fatty alcohols and of sorbitan esters, and glycerol and sorbitan esters of fatty acids. Various dispersing or suspending agents can be included and representative ones are synthetic and natural gums, tragacanth, acacia, alginate, dextran, gelatin, sodium carboxymethylcellulose, methylcelulose, polyvinylpyrrolidone, and the like. The proportion of the active compound in the aqueous suspensions of the invention can vary from about 1 percent to about 20 percent or more.

Oil solutions are preparedby mixing the active compound and an oil, e.g., an edible oil such as cotton seed oil, peanut oil, coconut oil, modified soybean oil, and sesame oil. Usually, solubility in oil will be limited and oil suspensions can be prepared by mixing additional finely divided compound in the oil.

Oil in water emulsions are prepared by mixing and dispersing an oil solution or suspension of the active compound in water preferably aided by surface-active agents and dispersing or suspending agents as indicated above. a

In general, the formulations of this invention are administered to animals so as to achieve therapeutic or prophylactic levels of the active compound. At present, it is known that 100 mgJkg. of body weight in lambs will effectively combat a wide variety of parasitic worms. Much lower effective dosages are contemplated, e.g., in the range of 25 to mg./kg. of body weight.

In other animals, and for other kinds of parasitic worms, definitive dosages can be proposed. Contemplated are dosage rates of about 1 mg. to about 800 mg. per kg. of body weight. A preferred, contemplated range of dosage rates is from about mg. to about 400 mg. per kg. of body weight. In this regard, it should be noted that the concentration of active compound in the formulation selected for administration is in many situations not critical. One can administer a larger quantity of a formulation having a relatively low concentration and achieve the same therapeutic or prophylactic dosage as a relatively small quantity of a relatively more concentrated formulation. More frequent small dosages will likewise give results comparable to one large dose. Unit dosage forms in accordance with this invention can have anywhere from less than 1 mg. to 500 g. of active compound per unit.

If desired the solid unit dosage forms of this invention including pellets and granules can be coated so as to provide timed release in the digestive system of animals. Such laminated or enteric coated forms are prepared by appropriately applying to a pill or bolus a polymeric acid or a mixture of a polymeric acid with shellac, and cetyl alcohol, cellulose acetate, or styrene maleic acid copolymer.

The new anthelmintic at or ar (alkylthio) benzoyl chloride phenylhydrazones of Formula 1, above, are

readily prepared by reacting a selected ar or ar (alkylthio). benzoic acid Z-phenylhydrazide with phosphorus pentachloride, reacting the resulting, corresponding ar or ar (alkylthio) benzoyl chloride (dichlorophosphinyl)phenylhydrazone with phenol,

Step 1. of the foregoing process proceeds when a new ar or ar (alkylthio) benzoic acid 2-phenylhydrazide starting compound (compounds of Formula 11, above) and the phosphorus pentachloride are mixed in the presence of a reaction medium at a temperature in the range of about C. up to about the boiling point of the reaction medium. Higher and lower temperatures can be used, however. The reaction rate will be decreased at low temperatures, and a pressure vessel would be needed to effect reaction temperatures above the boiling point at atmospheric pressure. In accordance with a preferred embodiment, the initial reaction mixture is heated.

Appropriate reaction media include, for example, the chlorinated hydrocarbon solvents, aliphatic or aromatic hydrocarbon solvents, and ethers. Representative specific ones are carbon tetrachloride (preferred),

methylene chloride, chloroform, 1,2-dichloroethylene, benzene, toluene, technical hexane, diethyl ether, and dioxane.

The process can be practiced without isolating the new ar or ar (alkylthio benzoyl chloride (dichlorophosphinyl)phenylhydrazone intermediate when three equivalents or more of phenol are added to the initial reaction mixture after it has been cooled to about 0 to 25 C. The phenol reacts with the new ar or ar (alkylthio) benzoyl chloride (dichlorophosphinyl)phenylhydrazone intermediate to produce triphenyl phosphate, and the desired new ar or ar (alkylthio) benzoyl chloride phenylhydrazone is then recovered and purified by conventional methods. The solvent medium is removed by evaporation, and the desired 7 product is recovered, e.g., by filtration from the residual triphenyl phosphate or by chromatographic techniques. The compound is purified by recrystallization.

The new ar or ar (alkylthio) benzoic acid Z-phenylhydrazide starting compounds of Formula 11 can be readily prepared by known methods. According to one method an (alkylthio) benzoyl chloride is reacted with a phenylhydrazine as described by J. Hausknecht, Chem. Ber. 22, p. 324 (1889), and E. Bamberger and W. Pemsel, Chem. Ber. 36, p. 359 (1903). Another method is described in U.S. Pat. No. 2,912,461, issued Nov. 10, 1959, that utilizes a benzoate ester and a phenylhydrazine. Still another method described by W. Autenrieth and G. Thomae, Chem. Ber. 57, p. 423 (1924) reacts a benzoic acid anhydride with a phenylhydrazine to produce the corresponding benzoic acid 2-phenylhydrazide. The Examples hereinafter illustrate conventional methods for making (alkylthio) benzoic acid 2-phenylhydrazide and benzoic acid 2-(alkylthiophenyl)hydrazide intermediates for starting compounds. The various (alkylthio) benzoyl chloride (substituted-phenyl)hydrazine and [(alkylthio)phenyl ]hydrazine starting compounds are prepared according to conventional methods.

The new anti-arthropodal ar or ar (alkylthio) benzoyl chloride phenylhydrazones of this invention (compounds according to Formula 1) can also be prepared by chlorinating an ar or ar (alkylthio) benzaldehyde phenylhydrazone. Chlorination of an ar or ar (alkylthio)benzaldehyde phenylhydrazone can be accomplished as described by J. E. Humphries, H. Humble and R. Evans, J. Chem. Soc. 127, p. 1304 (1925). But this chlorination is of limited usefulness when the starting ar or ar (alkylthio)benzaldehyde phenylhydrazone has unsubstituted active sites that will yield to chlorination at positions on the phenylhydrazone portion that are desired to remain unsubstituted in a particular instance. Direct chlorination of an (alkylthio)benzaldehyde phenylhydrazone is an effective way of producing (alkylthio)benzoyl chloride (2,4,6-trichlorophenyl)hydrazone.

Still another method described by L. A. Jones, C. K. Hancock, and R. B. Seligman, J. Org. Chem. 26, p. 228 (1961) can be used. The described method utilized a,a,a2,4 -dinitrophenylhydrazine to produce benzoyl chloride 2,4-dinitrophenylhydrazone. The new compounds of this invention can be prepared in the same manner.

EXAMPLE 1 Preparation of p-(Methylthio)benzoyl Chloride Phenylhydrazone Part A p-(Methylthio)benzoic Acid Z-phenylhydrazide A mixture consisting of 21.88 g. (0.130 mole) p- (methylthio)benzoic acid and 25 ml. thionyl chloride was heated at the reflux temperature until evolution of gas ceased and a clear solution was obtained. After removing the excess thionyl chloride on a rotary evaporator and then under substantially complete vacuum, the solid-residue that remained was dissolved in 35 ml. dioxane. The dioxane solution was mixed with asolution consisting of 14.06 g. (0.130 mole) phenylhydrazine in 100 ml. pyridine initially at to C. 1nadvertently, about one-third of the acid chloride was added rapidly and the mixture was heated to 31 C. by the exothermic reaction. The reaction mixture was set aside at 25 C. with continuous stirring for 3 days. It was then poured into 1.5 1. water in order to precipitate the desired p-(methylthio)benzoic acid 2-phenylhydrazide. The precipitate was collected on a filter, washed with water, washed with 1N hydrochloride acid, and finally washed with water. The washed filter'cake was then recrystallized from 3A alcohol to give 23.2 g. (69 percent yield) of p-(methylthio)benzoic acid 2-phenylhydrazide having a melting point at 165.5 to 167.5 C. Recrystallization from 250 ml. ethyl acetate gave the compound melting at 167 to 168 C. (shrinks at 162 C.). Two further recrystallizations from ethyl acetate gave the compound melting at 167 to 168.5 C. with shrinkage at 161.5C.

Analysis:

Calcd. for C H N,OS: C, 65.09; H, 5.46; N, 10.84;

s, 12.41. Found: C, 64.80; H, 5.57; N, 10.80;S, 12.34.

i Part B p-(Methylthio)benzoyl Chloride Phenylhydrazone A mixture consisting of 14.2 g. (0.068 mole) phosphorus pentachloride, 100 ml. 1 carbon tetrachloride, and 16.78 g. (0.065 mole) p- The solution was chilled in ice and a suspension of 20.7

g. (0.22 mole)phenol in 50 ml. carbon tetrachloride was added. After removing the carbon tetrachloride by evaporation on a rotary evaporator at 31 C. the resulting suspension of product in triphenylphosphate was filtered. The filter cake was washed with technical hexane (Skellysolve B, a mixture of isomeric hexanes having a boiling range between 146 and 156 Fahrenheit), and then was washed with diethyl ether. Crystallization from 75 ml. ethyl acetate gave 8.10 g. (44.9 percent yield) of p-(methylthio)benzoyl chloride phenylhydrazone having a melting point of-138.5".to 142.5" C. Recrystallization from a mixture of ethyl acetate and the Skellysolve B gave the compound with the same melting point. Analysis: Calc'd. for C, H ClN,S: C, 60.75; H, 4.73; Cl,

12.81;N,10.12;S,11.59' Found: C, 60.41; H, 4.76; CI,

EXAMPLE 2 Preparation of Benzoyl Chloride [p-(Methylthio)phenyllhydrazone Part A Benzoic Acid Z-(Methylthio)phenyl]hydrazide After dispersing and suspending 19.15 g. (0.100 mole) [p-(methylthio)phenyl]hydrazine hydrochloride in 500 ml. benzene, 10.1 g. (0.100 mole) triethylamine was added. The resulting suspension was stirred for two hrs. at 25 C. After adding 22.6 g. (0.100 mole) benzoic anhydride, the reaction mixture was heated at the reflux temperature for 4 hrs. The benzene was then removed by evaporation, and the residue thus obtainedwas washed once with water, twice with aqueous sodium bicarbonate, and finally with water. The washed residue was recrystallized once from 3A alcohol and once from a'mixture cyclohexane and ethyl acetate to 'give l5.0 g. (57.9 percent yield) of benzoic acid 2-[p- (methylthio)phenyl]hydrazide having a melting point at l39 to C.

Analysis:

Calcd. for C,,11,,N,os:c, 65.08; H, 5.46; N, 10.85.

Found: C, 65.01; H, 5.70; N, 10.59. Part B Benzoyl Chloride [p-(Methylthio)phenyl]hy drazone mole) phosphorus evaporation benzoyl A mixture consisting of 7.9 g. (0.038 mole )phosphorus pentachloride, 100 ml. carbon tetrachloride, and 9.05 g. (0.035 mole) benzoic acid 2- [p-(methylthio)phenyl]hydrazide (prepared in Part A above) was heated at the reflux temperature until evolution of gas ceased. The reaction mixture was chilled in ice, and a suspension of 11.3 g. (0.12 mole) phenol in 50 ml. carbon tetrachloride was added. After removing the carbon tetrachloride by evaporation under reduced pressure, the resulting triphenylphosphate solution of the desired product was poured through a column of silica gel. The column was eluted with a mixture of 1 part benzene and 1 part Skellysolve B. After removing the solvents from the eluate by evaporagtion under reduced pressure, the residue was recrystallized two times from cyclohexane to give genzoyl chloride [p-(methylthio)phenyl]hydrazone having a melting point at 94 to 95 C. Analysis: Calcd. for C H CIN S: C, 60.75; H, 4.73; Cl,

12.81;N, 10.12;S,11.59. Found: C, 60.77; H, 5.00; Cl, 13.08; N, 10.07; S,

EXAMPLE 3 Preparation of o-(Methylthio)-chlorobenzoyl' Chloride Phenylhydrazone Part A o-(Methylthio)benzoic Acid Z-phenylhydrazide to a solution consisting of 23.2 g. (0.214 mole) phenylhydrazine and ml. pyridine was added a chilled solution consisting of 40.0 g. (0.214 mole) o- (rnethylthio)benzoyl chloride and 200 ml. dioxane. This reaction mixture was set aside at 25 for 2 days. It was then poured into 2.5 1. water in order to precipitate the desired product. The precipitate was collected on a filter and washed with water, with 1N aqueous hydrochloric acid, and finally with water. The washed filter cake was recrystallized from 3A alcohol to give 36.8 g. (66.5 percent yield) of o-(methylthio)benzoic acid 2-phenylhydrazide having a melting point at 127 to 128 C.

Analysis: Calcd. for C H N OS: N, 10.84; S, 12.41. Found: N, 10.75; S, 11.98. Part B o-(Methylthio)-chlorobenzoyl Chloride Phenylhydrazone A mixture consisting of 21.9 g. (0.105 mole) phosphorus pentachloride, 150 ml. of carbon tetrachloride, and 25.83 g. (0.100 mole) o- (methylthio)benzoic acid 2-phenylhydrazide (prepared in Part A above) was heated at the reflux temperature until evolution of hydrogen chloride ceased. The reaction mixture was chilled in an ice-bath, and a suspension of 31.5 g. (0.335 mole) phenol in 50 ml. carbon tetrachloride was added. After removing the carbon tetrachloride by evaporation under reduced pressure, the resulting triphenylphosphate solution of the desired product was poured through a column of silica gel. Elution was effected with a mixture consisting of 1 part benzene and l part Skellysolve B. After removing the solvents from the eluate by evaporation under reduced pressure, 2.0 g. of residue was obtained. Recrystallization from petroleum ether gave an o-(methylthio)- chlorobenzoyl chloride phenylhydrazone having a melting point at 65 to 665 C.

Analysis:

Calcd. for C H Cl N Sz C, 54.02; H, 3.89; Cl,

22.78; N, 9.00; S, 10.30. Found: C, 54.09; H, 3.76; Cl,,22.77; N, 9.02; S,

EXAMPLE 4 Preparation of p-(Methylthio)ber|zoyl Chloride (2,4- Dibromophenyl)hydrazone To an ice-cold solution of 5.0 g. (0.018 mole) p- (methylthio)benzoyl chloride phenylhydrazone in 200 ml. carbon tetrachloride is added 7.2 g. (0.045 mole) bromine dissolved in 25 ml. carbon tetrachloride. The solution is heated at the reflux temperature for 4 hrs., and then the carbon tetrachloride is removed by evaporation under reduced pressure. The residue thus obtained is recrystallized to give the desired p- (methylthio)b enzoyl chloride (2,4-dibromophenyl)hydrazone.

EXAMPLE 5 3-bromo-2-nitro-5-(methylthio)benzoic acid, and 2-chloro-5-(n-hexylthio)benzoic acid for p- (methylthio)benzoic acid there is prepared 3-fluoro-4-(methylthio)benzoic acid Z-phenylhydrazide, m-(methylthio)benzoic acid 2-phenylhydrazide, p -(ethylthio)benzoic acid 2-phenylhydrazide,

p-(isopropylthio)benzoic acid 2-phenylhydrazide, p-(n-hexylthio)benzoic acid 2-phenylhydrazide, 2,6-dichloro-4-(methylthio)benzoic acid 2-phenylhydrazide, 3-iodo-4-(methylthio)benzoic acid Z-phenylhydrazide,

2-bromo-4-(methylthio)benzoic acid 2-phenylhydrazide,

2-bromo-5-chl0ro-4-(methylthio)benzoic acid 2- phenylhydrazide, 2-methyl-4-(methylthio)benzoic acid Z-phenylhydrazide,

3-ethyl-5-(ethylthio)benzoic acid 2-phenylhydrazide,

3-(n-hexyl)-4-(methylthio)benzoic acid 2-phenylhydrazide,

acid 2- acid 2- acid 2-phenyl- EXAMPLE 6 Following the procedure of Example 2, Part A, but substituting [3-bromo-5-(methylthio)phenyl]hydrazine, [3-chloro-5-(methylthio)phenyl]hydrazine, [.4-ethyl-2-(methylthio)phenyl]hydrazine, [2,6-diiodo-4-(methylthio)phenyl]hydrazine, [3,5-di(methylthio)phenyllh'ydrazine,

[p-(n-hexylthio)phenyllhydrazine, for [p- (methylthio)phenyl]hydrazine and p-(methylthio)benzoic anhydride and (pbromophenyl)hydrazine,

m-(methylthio )benzoic anhydride and (pchlorophenyl)hydrazine, m-(methylthio)benzoic anhydride and (p-nitrophenyl)hydrazine, m-(methylthio)benzoic diiodophenyl)hydrazine, I m-(methylthio)benzoic anhydride and (p-ethylphenyl)hydrazine, m-(methylthio)benzoic anhydride isopropylphenyl)hydrazine, m-(methylthio)benzoic anhydride and [m-(n-hexyl)phenyl]hydrazine,

anhydride and (2,4-

and (mm-(methylthio)benzoic acid nitrophenyl) hydrazide, m-(methylthio)benzoic acid (trifluoromethyl)phenyl]hydrazide,

2-(3-methyl-4- 2-[3-methyl-S- m-(methylthio)benzoic acid [p-(methylthio)phenyllhydrazide,

m-(methylthio)benzoic acid 2-[3-(methylthio)-5- (trifluoromethyl)phenyllhydrazide,

m-(methylthio)benzoic acid 2-[p-fluorophenyl] hydrazide,

and

3-methylthio)-5-(n-hexyl)benzoic acid 2-[3,5-di-nbutyl-4-(methylthio)phenyl]hydrazide for p- (methylthio)benzoic acid 2-phenylhydrazide, there are prepared 3-fluoro-4-(methylthio)benzoyl chloride phenylhydrazone,

m-(methylthio')benzoyl chloride phenylhydrazonc,

p-(ethylthio)benzoyl chloride phenylhydrazone,

p-(isopropylthio)benzoy l chloride phenylhydrazone, p-(n-hexylthio)benzoyl chloride phenylhydrazone, 2,6-dichloro-4-(methylthio)benzoyl chloride phenylhydrazone,

3-iodo-4-(methylthio)benzoyl chloride phenylhydrazone,

2-bromo-4-methythio)benzoyl chloride phenylhydrazone, 2-bromo-5-chloro-4-(methylthio)benzoyl chloride phenylhydrazone, 2-methyl-4-(methylthio)benzoyl chloride phenylhydrazone, 3-ethyl-5-(ethylthio)benzoyl chloride phenylhydrazone,

3-(n-hexyl)-4-(methylthio)benzoyl chloride phenylhydrazone,

3-isopropyl-5-(methylthio)benzoyl chloride phenylhydrazone, 2-chloro-4-methyl-5-(methylthio)benzoyl chloride phenylhydrazone, 2,6-dibrom0-3-ethyl-5(methylthio)benzoyl chloride phenylhydrazone,

3-(methylthio)-4-nitrobenzoyl chloride phenylhydrazone, 3-(methylthio)-5-trifluoromethylbenzoyl chloride phenylhydrazone, 2-(a,a-difluoroethyl)-4-(methylthio)benzoyl chloride phenylhydrazone, 3,5-di(methylthio)benzoyl chloride phenylhydrazone, I 2,3,5-tri(methylthio)benzoyl chloride phenylhydrazone, 3-bromo-2-nitro-5-(methylthio)benzoyl chloride phenylhydrazone, 2-chloro-5-(n-hexylthio)benzoyl chloride phenylhydrazone,

benzoyl chloride 2-[3-bromo-5-(methylthio)phenyllhydrazone,

benzoyl chloride 2-[3-chloro-5-(methylthio)phenyllhydrazone,

benzoyl chloride 2-[4-ethyl-2-(methylthio)phenyl]hydrazone,

benzoyl chloride 2-[2,6-diiodo4-(methylthio)phenyllhydrazone,

benzoyl chloride 2-[3,5-di)methylthio)phenyl]h ydrazone,

benzoyl chloride 2-[p-(n-hexylthio)phenyl] hydrazone,

p-(methylthio)benzoyl chloride (p-bromophenyl)hydrazone,

m-(methylthio)benzoyl chloride (p-chlorophenyl)hydrazone,

m-(methylthio)benzoyl chloride (p-nitrophenyl)hydrazone,

m-(methylthio)benzoyl chloride (2,4-diiodophenyl)hydrazone,

m-(methylthio)benzoyl chloride (p-ethylphenyl)hydrazone,

m-(methylthio)benzoyl chloride (m-isopropylphenyl)hydrazone,

m-(methylthio)benzoyl chloride [m-(n-hexyl)phenyllhydrazone,

m-(methylthio)benzoyl choride [p- (trifluoromethyllphenylflhydrazone,

m-(methylthio)benzoyl chloride (2-chloro-4- nitrophenyl)hydrazone,

m-(methylthio)benzoyl chloride (3-methyl-4- nitrophenyl)hydrazone,

m-(methylthio)benzoyl chloride [3-methyl-5- (trifluoromethyl)phenyl]hydrazone,

m-(methylthio)benzoyl chloride [p- (methylthio)phenyl1hydrazone, m-(methylthio)benzoyl chloride [3-(methylthio)-5- (trifluoromethyl)phenyl]hydrazone, m-(methylthio)benzoyl chloride (p-fluorophenyl)hydrazone, and 3-(methylthio)-S-(n-hexyl)benzoyl chloride [3,5-din-butyl-4-(methylthio)phenyl]hydrazone, respectively In the formulas l and ii, above, the substituent group a-F alkyl is an alkyl group of from one to three carbon atoms, inclusive, having the a-carbon substituted with fluorine atoms, More particularly the substituent group is trifluoromethyl a,a-difluoroethyl, and a,adifluoroproply. Similarly alkylthio means methylthio, ethylthio, isopropylthio, hexylthio, and the like.

Iclaim:

l. The method of killing and controlling parasitic worms in animals which comprises administering to an animal a therapeutic or propylactic dosage of an ar or ar' (alkylthio) benzoyl chloride phenylhydrazone having the structural formula wherein alkyl" is of from one to six carbon atoms, inclusive; X is halogen, alkyl of from one to six carbon atoms, inclusive, alkylthio of from one to six carbon atoms, inclusive, a-F alkyl of from one to three carbon atoms, inclusive, wherein n is the integer 2or 3, and nitro; Y is alkyl of from one to six carbon atoms, inclusive, halogen, alkylthio of from one to six carbon atoms, inclusive, a-F alkyl of from one to three carbon atoms, inclusive, and nine; n is an integer 0 to 3, inclusive; n" .is 1 except when Y is alkylthio, when it can be zero; m is an integer from 0 to 3, inclusive, the sum of n+n"+m being not more than 6, the sum of carbon atoms in the alkyl substituents being not more than 15,

, (methylthio)phenyl]hydrazone.

compound p-(methylthio)benzoyl chloride phenylhydrazone itself is administered.

3. The method according to claim 1 wherein n" is one and the S-alkyl" group is in the para position.

4. The method according to claim 3 wherein n is zero.

5. The method according to claim 4 wherein m is zero.

6. The method'according to claim 3 wherein the S- alkyl group is methylthio.

7. The method according to claim 6 wherein n is zero.

8. The method according to claim 1 wherein Y is alkylthio and n" is'zero.

9. The method according to claim 8 wherein alkylthio is methylthio. I I

10. The method according to claim 9 wherein benzoyl chloride [p-(methylthio )phenyllhydrazone.

1-1. The method according to claim 1 wherein ovines are treated.

12. The method according to claim 1 wherein the active agent is administered in the form of a capsule.

13'. The method according to claim 12 wherein ovines are treated with p-(r'nethylthio)benzoyl chloride I phenylhydra'zone.

14. The method according to claim 12 wherein ovines are ,treated with benzoyl 15. A unit dosage formulation for administration to animals for the purpose of killing and controlling parasitic worms in said animals' comprising a physiologically acceptable carrier and adjuvants, and at least an effective amount of an at or ar' '(alkylthio) benzoyl chloride phenylhydrazone having the structuralformu- .wherein alkyl is of from one to six carbon atoms, in-

inclusive, and nitro; n is an integer to 3, inclusive; n"

is 1 except when Y is alkylthio, when it can be zero, m is an integer from. 0 to 3; inclusive, the sum of n+ n m being not more than 6, the sum of carbon atoms in the alkyl substituen'ts being not more than 15,.there being no more than one nitro group in the molecule, and mo more than two S-alkyl groups on any benzene ring or three total.

l6 Formulation according to claim 15 comprising thespecific compound p-(methylthio)benzoyl chloride phenylhydrazone.

17. Formulation according to claim 15 wherein n" is one and the "S-alkyl" group is in the para position.

18. Formulation according to claim 17 wherein the n" is zero.

19. Formulation according to claim 18 wherein m is zero. I

20. Formulation according to claim 15 wherein the carrier and active compound are combined in unit dosage form having from less than 1 mg. to 500 g. of active compound.

21. Formulation according to claim 20 wherein a surface active agent compound is included.

22. Formulation according to claim 21 comprising the specific compound p-(methylthio)benzoyl chloride phenylhydrazone. I

l 23. Formulation according to claim 21 comprising the specific compound benzoyl chloride [p- (methylthio)phenyl]hydrazone.

24. Formulation according to claim 21 wherein n" is one and the S-alkyl" group is in the para position.

25. Formulation according to claim 24 wherein the n' .is zero. 4

26. Formulation according to claim 25 wherein m is zero.

27. A therapeutic formulation comprising in encapsulated form a dispersible carrier and from about 50.

mg. to about 25 grns. of an ar or ar' (alltylthio) benzoyl chloride phenylhydrazone having the structural formu chloride [p- (S-alkyUn 01 H (Y)m.

wherein alkyl" is of fromone to six carbon atoms, inclusive; X is halogen, alkyl of from one to six carbons atoms, inclusive; alkylthio of from one to six carbon atoms, inclusive, a-F alkyl of from one to three carbon atoms, inclusive, wherein n is the integer 2 or.3, and nitro; Y is alkyl of from one to six carbon atoms, inclusive, halogen, alkylthio of from one to six carbon atoms, inclusive, a-F alkyl of from one to three carbon atoms, inclusive, and nitro'; n" is an integer 0 to 3, inelusive; n" is 1 except when Y is alkylthio, when it can be zero; m is an integer from 0 to 3, inclusive, the sum of n'+n"+m being not more than 6, the sum of carbon atoms in the alkyl substitutents being not more than 15, there being no more than one nitro group in the molecule, and no more than two alkyl groups on any benzene ring or three total.

' 28. Formulation according to claim 27 wherein the dispersible carrier isa liquid.

29. Formulation according to claim 27 wherein the dispersible carrier is a finely divided solid.

30. Formulation according to claim 29 comprising the specific compound p-(methylthio)benzoyl chloride phenylhydrazone.

31. Formulation according to claim' 29 comprising specific compound benzoyl chloride [p- (methylthio)phenyl]hydrazone.

32 Formulation according to claim 27 wherein n" is one arid the S-alkyl" group is in the para position.

' 33. Formulationaccording to claim 22 wherein n is zero. I

34. Formulation according to claim 33 wherein m is 

2. The method according to claim 1 wherein the compound p-(methylthio)benzoyl chloride phenylhydrazone itself is administered.
 3. The method according to claim 1 wherein n'''' is one and the ''''S-alkyl'''' group is in the para position.
 4. The method according to claim 3 wherein n'' is zero.
 5. The method according to claim 4 wherein m is zero.
 6. The method according to claim 3 wherein the ''''S-alkyl'''' group is methylthio.
 7. The method according to claim 6 wherein n'' is zero.
 8. The method according to claim 1 wherein Y is alkylthio and n'''' is zero.
 9. The method according to claim 8 wherein alkylthio is methylthio.
 10. The method according to claim 9 wherein benzoyl chloride (p-(methylthio)phenyl)hydrazone.
 11. The method according to claim 1 wherein ovines are treated.
 12. The method according to claim 1 wherein the active agent is administered in the form of a capsule.
 13. The method according to claim 12 wherein ovines are treated with p-(methylthio)benzoyl chloride phenylhydrazone.
 14. The method according to claim 12 wherein ovines are treated with benzoyl chloride (p-(methylthio)phenyl)hydrazone.
 15. A unit dosage formulation for administration to animals for the purpose of killing and controlling parasitic worms in said animals comprising a physiologically acceptable carrier and adjuvants, and at least an effective amount of an ar or ar'' (alkylthio) benzoyl chloride phenylhydrazone having the structural formula:
 16. Formulation according to claim 15 comprising the specific compound p-(methylthio)benzoyl chloride phenylhydrazone.
 17. Formulation according to claim 15 wherein n'''' is one and the ''''S-alkyl'''' group is in the para position.
 18. Formulation according to claim 17 wherein the n'''' is zero.
 19. Formulation according to claim 18 wherein m is zero.
 20. Formulation according to claim 15 wherein the carrier and active compound are combined in unit dosage form having from less than 1 mg. to 500 g. of active compound.
 21. Formulation according to claim 20 wherein a surface active agent compound is included.
 22. Formulation according to claim 21 comprising the specific compound p-(methylthio)benzoyl chloride phenylhydrazone.
 23. Formulation according to claim 21 comprising the specific compound benzoyl chloride (p-(methylthio)phenyl)hydrazone.
 24. Formulation according to claim 21 wherein n'''' is one and the ''''S-alkyl'''' group is in the para position.
 25. Formulation according to claim 24 wherein the n'' is zero.
 26. Formulation according to claim 25 wherein m is zero.
 27. A therapeutic formulation comprising in encapsulated form a dispersible carrier and from about 50 mg. to about 25 gms. of an ar or ar'' (alkylthio) benzoyl chloride phenylhydrazone having the structural formula:
 28. Formulation according to claim 27 wherein the dispersible carrier is a liquid.
 29. Formulation according to claim 27 wherein the dispersible carrier is a finely divided solid.
 30. Formulation according to claim 29 comprising the specific compound p-(methylthio)benzoyl chlOride phenylhydrazone.
 31. Formulation according to claim 29 comprising the specific compound benzoyl chloride (p-(methylthio)phenyl)hydrazone.
 32. Formulation according to claim 27 wherein n'''' is one and the ''''S-alkyl'''' group is in the para position.
 33. Formulation according to claim 22 wherein n'' is zero.
 34. Formulation according to claim 33 wherein m is zero. 